Contour projector with means for adjusting the viewing angle



Jan. 18, 1966 R. J. MELTZER 3,229,572

CONTOUR PROJECTOR WITH MEANS FOR ADJUSTING THE VIEWING ANGLE OriginalFiled May 19, 1960 2 Sheets-Sheet 1 FIG.

FOCAL PLANE INVENTOR. ROBERT J. MELT ZER A TTORNEYS Jan. 18, 1966 J.MELTZER CONTOUR PROJECTOR WITH MEANS FOR ADJUSTING THE VIEWING ANGLE 2Sheets-Sheet 2 Original Filed May 19, 1960 m m m m ROBERT J. MELT ZEIRATTORNEYS United States Patent Ofifice 3,229,572 Patented Jan. 18, 19663,229,572 CONTOUR RROJECTOR WITH MEANS FOR ADJUSTING THE VEWING ANGLERobert J. Meltzer, Irondequoit, N.Y., assignor to Bausch & LomhIncorporated, a corporation of New York Original application May 19,1960, Ser. No. 30,282, new Patent No. 3,099,185, dated July 36, 1963.Divided and this application .iune 27, 1963, Ser. No. 292,203

3 Claims. (Cl. 88-24) This is a division of application Serial No.30,282, now Patent No. 3,099,185, filed May 19, 1960.

This invention relates to improvements in optical viewing devices, andmore particularly, but not necessarily exclusively, to an improvedcontour projector, or projection micro-scope including means for varyingthe direction of the optical axis in the object space in order to adjustthe angle at which an object is viewed.

The invention has to do especially with the problem of viewing theprofile of an object having a helical configuration, and of takingsuccessive profile views progressively along the length of such anobject. In the measurement of screw threads and the like, for example,by optical means, it is desired to view profile images of successiveportions of the thread along the length of the screw. For this purpose,the viewing device and the screw must be aligned for each view in such away that the optical axis of the viewing device is parallel to the screwthread along the line of view. In prior art contour projectors theviewing axis has been fixed, and it has been necessary to mount thestage upon ways, which are in turn mounted on a turntable in order toprovide for convenient traverse along the length of a helical profilewhile maintaining the desired alignment of the optical axis relative tothe helix.

Accordingly, one important object of the present invention is to providean improved optical viewing device including improved means formaintaining a desired alignment of the optical axis in the object spacerelative to the object to be viewed.

Other objects are: to provide an improved contour projector includingmeans for adjusting the direction of the optical axis in the objectspace thereby to bring the optical viewing axis into alignment with adesired viewing direction; to provide an improved arrangement of thistype in a contour projector, which permits traverse of the profile of anobject of helical configuration simply by moving the object in the samedirection as required for traversing an object of rectangularconfiguration; and, in general, to provide an improved arrangement ofthis character which is relatively simple and inexpensive tomanufacture, easy to use, and rugged and long lasting in service.

The foregoing and other objects and advantages of the present inventionwill become apparent in the following detailed description of arepresentative embodiment thereof, taken in conjunction with thedrawing, wherein:

FIG. 1 is a diagrammatic view of a contour projector including anadjusting arrangement according to a presently preferred embodiment ofthe invention;

FIG. 2 is a diagrammatic, front elevational view of a portion of thecontour projector shown in FIG. 1;

FIG. 3 is a partly diagrammatic, cross sectional view of an alternativearrangement according to the invention for varying the viewing angle ofa contour projector;

FIG. 4 is a side elevational View, partly in section, of a contourprojector generally similar to the projector illustrated in FIG. 1, butincluding a modified arrangement for controlling the direction of thelight provided for illuminating the object under observation;

FIG. 5 is a front elevational view of the contour projector illustratedin FIG. 4;

FIG. 6 is a side elevational view of the contour projector shown in FIG.1 as arranged for viewing with its viewing axis directed generallyupwardly; and

FIG. 7 is a front elevational view of the contour projector as shown inFIG. 6.

Contour projectors are widely used for viewing screw threads and othernon-rectilinear surfaces to determine the nature of the profiles andother configurational details of the surfaces. For this purpose, theviewing axis in the object space must be aligned with the surface underobservation in such a way that the profile it is desired to observe isnot shaded or concealed by parts of the object lying out of the plane ofview. With a screw thread, for example, viewing the screw must bearranged with its major axis on a diagonal, or screw direction relativeto the viewing axis. When it is desired to traverse a screw in a deviceof the type in which the viewing axis is fixed, it is necessary to movethe screw along such diagonal direction, which travel requires either anarrangement for adjusting the alignment of the ways on which the stagetravels, or a great deal of operator inconvenience. Heretofore, thestages of contour projectors intended for such work have usually beenmounted upon smoothly adjustable, calibrated turntables, called helixtables, in order to provide adjustment of the direction of travel of thestages. Such helix tables are relatively expensive, since they must besmooth in action and include a precisely controllable drive arrangement.

According to the present invention, means are provided in a contourprojector for controllably adjusting the direction of view in the objectspace, whereby the viewing axis may be aligned in accordance with adesired viewing angle without adjusting the workpiece, and a helicalprofile may be traversed simply by moving the workpiece perpendicularlyto the normal direction of the viewing axis, thus permitting arelatively simple and inexpensive stage construction. Also, in thepreferred construction, the viewing axis may be swung full circle, thuspermitting viewing in any desired direction according to the convem'enceof the operator and the type of work at hand.

Referring now to the drawing, the invention is illustrated in FIG. 1 asembodied in a contour projector of the general type described andclaimed in my co-pending application, Serial No. 10,790, now Patent No.3,064,523, filed February 24, 1960. The internal optical system of thecontour project-or may be of any desired type. As illustrated, itcomprises a telecentric afocal relay system including a front objectivelens 1t and a rear objective lens 12, which are spaced apart a distanceequal to the sum of their focal lengths. The afocal system projects anaerial image of the object 14 being viewed into an image plane 16, whichis disposed at a conjugate position relative to a view screen 18, withrespect to a projection lens 20. The aerial image is relayed by theprojection lens 20 from the image plane 16 to the view screen 13, andmay be enlarged to any desired degree depending upon the power of theprojection lens 20. If desired, additional projection lens such as thealternate lens 22 may be mounted on a turret 24 together with the lens20 for alternate insertion into the optical path to provide for variousdifferent degrees of magnification according to the requirements of thework and the operators convenience.

So-called vertical illumination for the object 14 is provided by aninternally mounted light source 26. Light from the light source 26 iscollimated by a collimating lens 28, and then reflected by a planemirror 30 to a re fractive member 32, which is positioned at the stop ofthe afocal telescentric system. The refractive member 32 is in the formof a Fresnel prism, and directs the illumination light into pathsgenerally parallel to the internal optical axis 34 of the afocal system.The light thus emerges through the front objective of the afocal systemand is directed toward the surface of the workpiece 14 for illuminatingit.

Profile illumination is provided by an external light source 36 mountedon the opposite side of the stage 38 from the front objective 10.Further details of the profile illumination arrangement will bedescribed hereinafter.

In the arrangement shown in FIGS. 1 and 2, a mirror 40 is mounted infront of the front objective to for directing the optical axis 41generally downwardly in the object space. Such an arrangement, whereinthe mirror is fixed in position is old. According to the invention,however, the mirror 40 is mounted for rotation about the fixed opticalaxis of the front objective lens 10. As shown, the mirror 40 is securedat the end of a tubular mounting member 44, which is fitted for smoothrotation within an aperture 46 in the face of the projector housing. Athumbscrew arrangement 48 is provided for releasably locking themounting member 44- against rotation after it has been set to a desiredangular position.

The workpiece 14 is illustratively shown as a screw having a helicalconfiguration. For convenience, it may be mounted between centers 54 and56 above the glass plate 58 of the stage 59, through which the profileillumination is projected. The screw 14 is mounted with its major axisgenerally horizontal, and for profile viewing of the screw 14, themirror 40 is rotated to a position where the viewing axis 41 isgenerally parallel to the direction of the screw thread in the desiredplane of view. The screw 14 may be traversed in the ordinary traversingdirection, that is along a path perpendicular to the internal viewingaxis 34 of the projector for viewing successive portions of its helicalprofile.

It is also desirable in this type of work to provide maximumillumination. Toward this end, means are provided for directing theprofile illumination approximately parallel to the optical viewing axis41. This is accomplished according to the present invention by providingan adjustable deviating device such as the prism 62 shown, in the pathof the profile illuminating light for adjustably changing the angle atwhich the light from the profile illumination source 36 is directedtoward the workpiece 14 and the rotatable mirror 40. The prism 62 ispreferably achromatic, and is mounted by any convenient means (notshown) for rotation in a horizontal plane. It is preferably removable topermit proper direction of the illumination when the rotatable mirror 40is adjusted for normal, vertical viewing.

It is appreciated that rotation of the prism 62 affects the direction ofillumination according to a circular pattern, and that as the directionis adjusted to coincide with the tilted viewing axis 41 in one plane itis diverted in the perpendicular plane. This however, has been found tobe not particularly objectionable and not to result in appreciable lossof illumination. The arrangement is a relatively simple one, as itprovides improved illumination relative to the illumination achieved byvertically directed light in those cases where the optical viewing axis41 is tilted more than a few degrees away from the vertical.

According to an alternate form of the invention as shown in FIG. 3, theviewing axis 41 of the contour projector may be controllably varied indirection by placing a pair of similar, counter rotatable prisms 70 and72 in the optical path between the objective 74 of the projector and theworkpiece 14. The prisms 70- and 72 are oriented for minimum deviationand are mounted in series along the viewing axis relatively close to thefront objective 74 of the contour projector for rotation in oppositeangular directions between a position in which they oppose each otherand a position in which their deviations are additive.

As shown, each mount 76 and 78 carries an external bevel gear 80 and 82,respectively, which meshes with a third, manually rotatable bevel gear84.

The degree of angular displacement of the viewing axis 60 achievable inthis modification of the invention is limited by the retracting power ofthe prisms 70 and 72, and in this respect, this modification is not asversatile as the embodiment shown in FIGS. 1 and 2. However, for mostpractical work, ample deviation of the viewing axis 60 may be achievedusing readily available achromatic prisms.

Since the prisms 70 and 72 rotate in opposition to each other, theviewing axis 60 is deviated in only one coordinate direction, thedeviation being maximum when the prisms are aligned with their wedgeprofiles in the same direction, and being minimum when the prisms arealigned with their wedge profiles facing in opposite directions. Anydeviation in the perpendicular coordinate direction, that is, in theplane perpendicular to the plane of the drawing, caused by one of theprisms 70 and 72 is compensated for and cancelled out by an equal andopposite deviation effected by the other one of the prisms 7i) and 72.

In the alternative arrangement illustrated in FIGS. 4 and 5, a mirror issupported beneath the stage 38 for reflecting the vertical illuminationback toward the object being viewed for profile illumination thereof.The mirror 90 is mounted upon the lower end of an arm 92, which is fixedto the rotatable mounting member 44, and is aligned perpendicularly tothe viewing axis 41. The mirror 96 may be used in conjunction with thevertical illumination system with the projector to provide profileillumination by reflecting the vertical illumination back toward theobject being viewed from the remote side thereof. Since the mirror 90 isalways in alignment with the viewing axis 41, regardless of the angularadjustment of the mounting member 44, no separate adjusting means isrequired in this embodiment for aligning the profile illumination withthe viewing axis.

A further advantage of making the mirror mounting member 44 rotatableabout the internal optical axis 34 of the projector is illustrated bythe arrangement shown in FIGS. 6 and 7. According to this arrangement,the viewing axis 41 is directed vertically upwardly by rotating themounting member 44 from its normal, downwardly looking position. A smallauxiliary stage is fitted over the open end of the mount 44 forsupporting a workpiece or for serving as a hand rest in the event it isdesired to hold the workpiece by hand. A downwardly directedillumina'tor 98 may be provided for profile illumination of theworkpiece in this arrangement, or alternatively, vertical illuminationmay be used either alone, or in conjunction with the mirror 90.

What is claimed is:

1. A contour projector comprising, an optical objective having a fixedoptical axis, a pair of counter-rotating deviating prisms arranged inseries in front of said objective controllably deviating the viewingdirection thereof, a source of illumination positioned in front of theobjective and spaced beyond the normal object space, refractive meansintermediate the normal object space and said source of illuminationvarying the direction of light from said source of light so that thelight is generally parallel with the viewing direction.

2. A contour projector comprising, an optical objective having a fixedoptical axis, a pair of deviating prisms arranged in series and axiallyaligned with the fixed optical axis in front of said objective forcontrollably deviating the viewing direction thereof, a source ofillumination located in front of said objective and spaced farthertherefrom than the normal object space, light concentrating meansconcentrating the light from said source and directing the light towardsaid objective, prism means receiving light from said lightconcentrating means varying the direction of light so concentrated sothat it is gen- References Cited by the Examiner erally parallel to saidviewing direction. UNITED STATES PA 3. A CODtOllI projector comprising,an optical obj c- 29 121 8/1906 Ncumayer 72 tive having a viewing axis,counter-rotating prism means 1,421,057 6/1922 Banfigki aligned with theoptical axis and positioned in front of 5 2,349,939 5/ 1944 Reason 38.24 X the objective for deviating the viewing direction, a source2,358,296 9/1944 Baty 8824 of illumination directing light toward saidobjective, prism 2,484,103 10/1949 Lfiwis 3824 means varying thedirection of light and aligning the light g; 23g;

substantially coincidental with the viewing axis of said 10 objectivethereby providing illumination of the object. NORTON ANSHER, PrimaryExamin

1. A CONTOUR PROJECTOR COMPRISING, AN OPTICAL OBJECTIVE HAVING A FIXEDOPTICAL AXIS, A PAIR OF COUNTER-ROTATING DEVIATING PRISMS ARRANGED INSERIES IN FRONT OF SAID OBJECTIVE CONTROLLABLY DEVIATING THE VIEWINGDIRECTION THEREOF, A SOURCE OF ILLUMINATION POSITIONED IN FRONT OF THEOBJECTIVE AND SPACED BEYOND THE NORMAL OBJECT SPACE, REFRACTIVE MEANSINTERMEDIATE THE NORMAL OBJECT SPACE AND SAID SOURCE OF ILLUMINATIONVARYING THE DIRECTION OF LIGHT FROM SAID SOURCE OF LIGHT SO THAT THELIGHT IS GENERALLY PARALLEL WITH THE VIEWING DIRECTION.